Bake multiple Armature animations within one file with IK
So, I did some more research and I found out that the blender collada exporter isn't able to export multiple animations within one file.

To fix my IK problem, I simply duplicated my armature several times. Than I used 1 armature/ animation to bake every animation. After that I was able to use my main armature connected to my mesh to select all the baked animations. That works pretty good, but nevertheless it's too bad collada doesnt support multiple animations. 

For now I am going with JSON.